1. Technical Field
The present disclosure relates to a semiconductor device.
2. Description of the Related Art
In the related art, semiconductor devices incorporating electronic components such as active elements and passive elements have various structures. In recent years, semiconductor devices having a wireless communication module incorporating, for example, a radio-frequency (RF) communication unit, a control unit, a crystal oscillator or the like have come to be used frequently in various fields. To perform a wireless communication using an antenna, such semiconductor devices are equipped with an antenna that is connected to the RF communication unit or the like (see e.g., JP-A-2007-324231).
FIG. 12 is a plan view of a related-art semiconductor device having an antenna 120. As shown in FIG. 12, the related-art semiconductor device 100 includes a wiring board 110 and a control IC chip 132 and an RF IC chip 131 which are mounted on the wiring board 110.
FIG. 13 is a plan view of the wiring board 110 in the related art. In FIG. 13, reference symbol R11 denotes a region where the RF IC chip 131 is to be mounted (hereinafter referred to as an RF IC mounting region R11) and symbol R12 denotes a region where the control IC chip 132 is to be mounted (hereinafter referred to as a control IC mounting region R12).
As shown in FIG. 13, the wiring board 110 has a board body 111, connection pads 112-115, traces 117-119, and an antenna 120. Each side surface of the board body 111 is formed with plural notches 111X. Each notch 111X is formed so as to assume a semicylindrical shape and to reach the top surface and the bottom surface of the board body 111.
The connection pads 112 and 113 are formed in the RF IC mounting region R11 of the top surface of the board body 111, and are electrically connected to the RF IC chip 131. The connection pads 112 are electrically connected to edge electrodes 116 via the traces 117, respectively. The connection pads 113 are electrically connected to connection pads 115 via the traces 118, respectively.
The connection pads 114 and 115 are formed in the control IC mounting region R12 of the top surface of the board body 111, and are electrically connected to the control IC chip 132. The connection pads 114 are electrically connected to edge electrodes 116 via the traces 119, respectively.
As shown in FIG. 14, the antenna 120 has wiring members 121 which are formed on the top surface of the board body 111, wiring members 122 which are formed on the bottom surface of the board body 111, and connection members 123 which are formed on respective notches 111X. The wiring members 121 and 122 and the connection members 123 are electrically connected mutually. The antenna 120 is electrically connected to the RF IC chip 131 shown in FIG. 12.
Forming the portions (i.e., connection members 123) of the antenna 120 on the side surface of the board body 111 makes it possible to decrease an area of the top surface of the board body 111 which is occupied by the antenna 120 than in the case where the antenna is formed only on the top surface of the board body 111.
However, in the above wiring board 110, the wiring length of the antenna 120 depends on the thickness of the board body 111. Therefore, when the board body 111 is thin, it is impossible to secure sufficient wiring lengths of the antenna 120 utilizing the connection members 123, resulting in difficulty designing a low-frequency antenna that requires a long wiring length. In this case, to design a low-frequency antenna, it is necessary to form long wiring members 121 and 122 on the top surface and the bottom surface, respectively, of the board body 111, which means increase in the areas occupied by the wiring members 121 and 122. That is, when the board body 111 is thin, a problem arises that it is difficult to reduce the horizontal area of the board body 111, that is, to miniaturize the board body 111, which in turn makes it difficult to miniaturize the semiconductor device 100 having the board body 111.